GB184825A - A new or improved process for the production of ethers of carbo-hydrates - Google Patents

Abstract

Alkyl ethers of cellulose, starch, dextrin and other carbohydrates of the general formula (C6H10O5)n, which are characterized by their insolubility in alcohol, benzene, and water, are obtained by treating the carbohydrates with alkyl chlorides at a temperature of 100-150 DEG C., in the presence of caustic alkali or other metallic hydroxide together with an amount of water not greater than half the weight of the alkali; it is preferred not to employ an excess of alkali, but an excess of alkyl chloride is used, preferably in the ratio of 20 molecular weights of the chloride to one molecular weight of the carbohydrate, taken as C6H10O5. The excess of alkyl chloride is eventually recovered, as by distillation. The reaction is facilitated by the addition of finely divided copper or other catalyst, and an inert organic diluent such as benzene may be added. In working the process, cellulose is soaked in 40 per cent caustic alkali solution, and afterwards pressed to give a product containing 2 parts of cellulose, 2-3 parts of caustic alkali, and 1-1 1/2 parts of water; alternatively, the ingredients in these proportions may be ground or mixed together; the etherification is carried out in one stage and usually in an autoclave, and in the case of ethyl and methyl chlorides at a temperature of 100 DEG C., but a higher temperature, preferably not exceeding 130 DEG C., is necessary with propyl, butyl and amyl chlorides, etc.; during etherification, the reacting-materials are preferably stirred or agitated. The ether is washed with water, and is purified by solution in glacial acetic acid with subsequent precipitation with water. Mixed ethers are obtained by employing a mixture of alkyl chlorides. The ethers may be employed in the manufacture of artificial threads, films, varnishes, plastic masses, &c.ALSO:Alkyl ethers of starch, dextrin and other carbohydrates of the general formula (C6H10O5)N, which are characterized by their insolubility in alcohol, benzene and water, are obtained by treating the carbohydrates with alkyl chlorides at a temperature of 100-150 DEG C., in the presence of caustic alkali or other metallic hydroxide together with an amount of water not greater than half the weight of the alkali; it is preferred not to employ an excess of alkali, but an excess of alkyl chloride is used, preferably in the ratio of 20 molecular weights of chloride to one molecular weight of carbohydrate taken as C6H10O5-the excess of alkyl chloride is eventually recovered, as by distillation. The reaction is facilitated by the addition of finely-divided copper or other catalyst, and an inert organic diluent such as benzene may be added. In working the process, cellulose is soaked in 40 per cent caustic alkali solution and afterwards pressed to give a product containing 2 parts of cellulose, 2-3 parts of caustic alkali, and 1-1 1/2 parts of water; alternatively, the ingredients in these proportions may be ground or mixed together; the etherification is carried out in one stage and usually in an autoclave, and in the case of ethyl or methyl chlorides at a temperature of 100 DEG C., but a higher temperature, preferably not exceeding 130 DEG C., is necessary with propyl, butyl, amyl chlorides, etc.; during etherification, the reacting-materials are preferably stirred or agitated. The ether is washed with water, and is purified by solution in glacial acetic acid and subsequent precipitation with water. Mixed ethers are obtained by employing a mixture of alkyl chlorides. The ethers may be employed in the manufacture of artificial threads, films, varnishes, plastic masses, &c.